Immunocytochemical analysis of microglia. Male C57BL/6J mice were treated intragastrically with ethanol (5 g/kg, i.g.) for 10 days and injected intraperitoneally (i.p.) with LPS (3 mg/kg, i.p.) 24 hrs after ethanol treatment. Mice were sacrificed 1 hr following saline or LPS injection. Brain sections were fixed and stained with Iba1 antibody. Ten daily doses of ethanol exposure potentiated LPS-induced microglial activation. In either LPS or ethanol treated groups, most of the microglia were in a resting morphological shape. However, in the ethanol pre-treated group, LPS increased Iba1 staining in some brain regions such as cortex, hippocampus and substantia nigra. Iba1-immunoreactive (IR) cells showed an increased cell size, irregular shape consistent with morphological changes in activated microglia.